1. Field of the Invention
The present invention relates to an endoscope and, more particularly, to an endoscope which is capable of obtaining functional information such as a bloodstream amount and an oxygen saturation rate by using picture data picked up by an optoelectronic device using light beams having different narrow-band wavelengths.
2. Description of the Prior Art
Recently, a variety of researches of a relation between a bloodstream state of a mucosa of an internal organ such as the stomach and the intestines of a subject and a disease thereof has been carried out in order to make clear the same, and a trial for utilizing measurements of functional information such as a bloodstream amount or a hemoglobin amount and an oxygen saturation rate by using a picture to conduct a diagnosis of a disease has been also carried out.
In the report titled to "SPECTRUM ANALYZER FOR MEDICAL TISSUE" of the literature "LASER RESEARCH", the 2nd number of the 13th volume, 1985, by Junichi HIRAMOTO and Masahiko KANDA, it is reported that a reflective spectrum of the mucosa of the stomach was measured to find certain relations between the bloodstream amount or the hemoglobin amount and the absorbance and between the oxygen saturation rate and the absorbance. In the report, there is shown in FIG. 1 an absorption spectrum of the hemoglobin in the blood of the human being, and in the drawing, at two points of wavelengths .lambda..sub.1 of 569 nm and .lambda..sub.3 of 586 nm, the spectrum values are not varied regardless of the variation of a ratio (SO.sub.2) of the oxidized hemoglobin amount with reference to the whole hemoglobin amount, and thus the two points of the wavelengths .lambda..sub.1 and .lambda..sub.3 are fixed points. However, when the ratio SO.sub.2 increases at a point of a wavelength .lambda..sub.2 of 577 nm, the spectrum value increases, and, in turn, when the ratio SO.sub.2 increases at a point of a wavelength .lambda..sub.4 of 650 nm, the spectrum value decreases. Hence, taking advantage of these characteristics of the hemoglobin, by measuring values indicated by segments a, b and c of the absorption spectrum of FIG. 1, the bloodstream amount or the hemoglobin amount (I.sub.HB) and the oxygen saturation rate (.sup.I SO.sub.2) can be obtained in accordance with the following formulas: EQU I.sub.HB =200.c
and
I.sub.SO.sub.2 =0.673.a/b
In the conventional method, when the measurement of the spectrum described above is carried out from one point to another point over the surface of the mucosa, it takes a long time to examine the entire wide surface. In an endoscopic detection, in particular, such an examination method will give a subject person considerable pain, and the object such as the stomach and the intestines to be examined is always in motion by peristalsis or a heart pulsation. Therefore, this method is not practical. Accordingly, it has been desired to measure the distributions of the bloodstream amount and the oxygen saturation rate as two-dimensional picture information in a short time. However, the conventional endoscope has no such a device for measuring the bloodstream amount and the oxygen saturation rate in the short time.